Web Forms :: Code Not Working In Internet Explorer

i want to send mail to user using checkbox selection within Grid View so i write this code using this website: [URL] But problem is this is working in mozilla but not in IE 8 , my IE enable script debugging. here is my code:

<table>
<tr>
<td>
Select User Type:
</td>
<td>
<asp:DropDownList ID="DropDownList1" runat="server" OnTextChanged="DropDownList1_TextChanged" AutoPostBack="true">
<asp:ListItem Text="--Select--" Selected="True" Value="1"></asp:ListItem>
<asp:ListItem Text="Free User"></asp:ListItem>
<asp:ListItem Text="Paid User"></asp:ListItem>
<asp:ListItem Text="All User"></asp:ListItem>
</asp:DropDownList>
</td>
</tr>
<tr>
<td colspan="2" align="center">
<script language="javascript" type="text/javascript">
function SelectAllCheckboxes(spanChk)
{
// Added as ASPX uses SPAN for checkbox
var oItem = spanChk.children;
var theBox=(spanChk.type=="checkbox")?spanChk:spanChk.children.item[0];
xState=theBox.checked;
elm=theBox.form.elements;
for(i=0;i<elm.length;i++)
if(elm[i].type=="checkbox" && elm[i].id!=theBox.id)
{
//elm[i].click();
if(elm[i].checked!=xState)
elm[i].click();
//elm[i].checked=xState;
}
}
</script>
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataKeyNames="uid">
<Columns>
<asp:boundfield DataField="uid" HeaderText="uid" ReadOnly="True" InsertVisible="False" SortExpression="uid" Visible="False">
</asp:boundfield>
<asp:boundfield DataField="nregistration" HeaderText="Registration" SortExpression="nregistration">
<ItemStyle Width="100px" />
</asp:boundfield>
<asp:boundfield DataField="nname" HeaderText="Name" SortExpression="nname">
<ItemStyle Width="100px" />
</asp:boundfield>
<asp:templatefield HeaderText="Email" SortExpression="nemail">
<ItemTemplate>
<asp:Label ID="lblemail" runat="server" Text='<%# Eval("nemail") %>'>
</asp:Label>
</ItemTemplate>
</asp:templatefield>
<asp:boundfield DataField="ntelephone" HeaderText="Telephone" SortExpression="ntelephone" Visible="False">
</asp:boundfield>
<asp:boundfield DataField="naddress" HeaderText="Address" SortExpression="naddress" Visible="False">
</asp:boundfield>
<asp:boundfield DataField="ndate" HeaderText="Date" SortExpression="ndate" Visible="False">
</asp:boundfield>
<asp:boundfield DataField="uname" HeaderText="uname" SortExpression="uname" Visible="False">
</asp:boundfield>
<asp:boundfield DataField="upassword" HeaderText="upassword" SortExpression="upassword" Visible="False">
</asp:boundfield>
<asp:boundfield DataField="usertype" HeaderText="UserType" SortExpression="usertype">
<ItemStyle Width="100px" />
</asp:boundfield>
<asp:boundfield DataField="umonth" HeaderText="Month" SortExpression="umonth">
<ItemStyle Width="100px" />
</asp:boundfield>
<asp:templatefield HeaderText="Select">
<HeaderTemplate>
<input id="chkAll" onclick="javascript:SelectAllCheckboxes(this);" runat="server" type="checkbox" title="xyz" />
</HeaderTemplate>
<ItemTemplate>
<asp:CheckBox ID="chkSelect" runat="server" />
</ItemTemplate>
</asp:templatefield>
</Columns>
</asp:GridView>
<asp:AccessDataSource ID="AccessDataSource1" runat="server" DataFile="~/database/profit_street.mdb"
SelectCommand="SELECT * FROM [registration]"></asp:AccessDataSource>
</td>
</tr>
<tr>
<td>
Subject: </td>
<td>
<asp:TextBox ID="TextBox1" runat="server" Columns="60"></asp:TextBox>
</td>
</tr>
<tr>
<td>
Message:
</td>
<td>
<asp:TextBox ID="TextBox2" runat="server" Columns="60" Rows="8" TextMode="MultiLine"></asp:TextBox>
</td>
</tr>
<tr>
<td colspan="2" align="center">
<asp:Button ID="Button1" runat="server" Text="Send Mail" OnClick="Button1_Click" ValidationGroup="x1"/>
</td>
</tr>
</table>

===========================In CS===================================
protected void DropDownList1_TextChanged(object sender, EventArgs e)
{
if (DropDownList1.SelectedItem.Text=="Free User")
{
con.Open();
OleDbCommand cmd = new OleDbCommand("select * from registration where usertype='Free User'", con);
OleDbDataReader red = cmd.ExecuteReader();
GridView1.DataSource = red;
GridView1.DataBind();
con.Close();
}
else if (DropDownList1.SelectedItem.Text=="Paid User")
{
con.Open();
OleDbCommand cmd = new OleDbCommand("select * from registration where usertype='Paid User'", con);
OleDbDataReader red = cmd.ExecuteReader();
GridView1.DataSource = red;
GridView1.DataBind();
con.Close();
}
else if (DropDownList1.SelectedItem.Text == "All User")
{
con.Open();
OleDbCommand cmd = new OleDbCommand("select * from registration", con);
OleDbDataReader red = cmd.ExecuteReader();
GridView1.DataSource = red;
GridView1.DataBind();
con.Close();
}
}
protected void Button1_Click(object sender, EventArgs e)
{
con.Open();
foreach (GridViewRow gv in GridView1.Rows)
{
CheckBox deleteChkBxItem = (CheckBox)gv.FindControl("chkSelect");
if (deleteChkBxItem.Checked)
{
StringBuilder str = new StringBuilder();
string strMail = ((Label)gv.FindControl("lblemail")).Text.ToString();
SmtpClient sc = new SmtpClient();
MailMessage mm = new MailMessage("webtechno.in@gmail.com", strMail);
mm.Subject = TextBox1.Text;
mm.Body = TextBox2.Text;
sc.EnableSsl = true;
sc.Send(mm);
Response.Write(strMail);
}
}
con.Close();
}